SPECIFICATIONS

FREQUENCY COVERAGE: 1.8-30 m1.. LINE. IMPEDANCE:

ACCURACY:

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FRONT PANEL: REMOVABLE COUPIL$

: hkati6n ., ~ote~~fom.e ters . One .5 : @ 5 pf pi@g?YWmmer null ad-

justaent.

DIMENSIONS MAIN CABINET: 55/18. highx 67/8"wide, 7" cabinet

depth (13.5 cm h, 17.5 cm w, 19 cm d) .

REMOVABLE COUPLER: 2%" high, 3%" wide, 2%'' deep WEIGHT: 2% lbs. (1.25 kG)

WH-7 INSTRUCTION MANjAL , ,

GENERAL

Description. , The Drake Model WH-7 Wattmeter is a through line wattmeter

which accurately measures forward and reverse power. The RF coupler is made removable so that i t may h- cnn-eniently located

. a t the output of the transmitter.

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INSTALLATION \

< Unpacking. .:' I [ . . Carefully remove the unit from the shipping carton, and examine i t for evidence of damage. 1f;any damage is discovered, irnmedi- ately notify the transportatioh company that delivered the unit..

makes packing the

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, , , . The WH-7 Wattmeter should be insta ... of the transmitter (or amplifier) and PL-259 coax connectors will couple correctly with the SO 239 receptacles on the sensing element. The sensing element is com- pletely removable for station convenience. I t can be removed by unscrewing the four machine screws on the bottom of the cabinet that hold i t in place. In this manner the sensing element can be installed behind the operating table so that bulky coax need not be brought up. Approximately 3 feet of cable connects the sensing element to the meter allowing a wide range of installation posi- tions. ',lib.

,:a\": 8 , . < VSWR Measurements. VSWR measurements may be made easily and directly with the WH-7. Turn the selector switch to:the 'SET' position (full CW) and a d j u ~ t the 'VSWR SET' contbl to align the meter pointer

[with 'SET' a t the full scale positid6 on the meter. Turn the se- lector switch to the;'VSWR' positi&$.and read the VSW@,,&ectly 1 from the VSWR sa$i!i (bottom scat#:. " , , I ,

appropriate scales of 'F FLECTED' power on calculated by subtracting

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Service. The WH-7 was designed to l$@$p maintenance to a minimum. Since the WH-7 is basically device, i t should provide years of service with proper c oblems arise that cannot ,~ ,,

solved easily, we sugg u either return your unit to your'j~ dealer, or write direc . L. Drake Service Departmenti describing your prob . Include full information con- ! : cerning external co trol settings, type of anterm,'J used, etc. Do not return equipment to,the factory with proper authorizatio request frir, .authorization

R. L. Drake C9mpany 540 Richard @feet Miamisburg, Ohio 45342 ATTN: CustoPner Telephone: (Area Code 513) 866-3211

TelexNo. 288-017

P The following e kpment is necessary;#T ,, alignment 'i ' I

load with an s V ? ~ of no more:$ l d l : ~ handling 1 kW. ';, ' , #

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b. An accurate 2 ~ . voltmeter such &the HP41QB or Boonton 91CA. i

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c. A transmitter with:variable output to 1kW a t 14.00 MHz. All adjustments aremadeat 14.00 MHz.

d. A short piece (3 inches) of 60 Ohm coax such as RGI8U or double malepLR59 connector.

:e. One insulated alignment tool.

Diode Replacement. Should either or both of the diode rectifiers malfunction,

they should be replaced only with the same type. Diodes with Remove the coupler from the Wattmeter and carefully remove

different characteristics may seriously impair the accuracy of the the screws and cover from the coupler exposing the printed cir- cuit board.

Wattmeter. -

Null Adju~Thf6ht. With the transmitter and dummy load connected to the respec- tive jarks on the coupler and the WH-7 range switch in the VSWR position, apply 1000 watts to the load. If any reflected power is visible, insert the alignment ;tool through the hole in the side of the coupler and adjust ttie piston trimmer for minimum reflect& power (VSWR Set control tdr:eed to extreme CW position). If the load is purely resistive, this $11 he essentia'lly zero. This correctly adjusts the 50 Ohm referenC$,level and no further adjustments of the piston trimmer will be &&ired.

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RG~;IIVVL -... pmer f th@,20 watt positio load and appiy po

WH-7 indicates exactly l0ypatts. 22.36 volts RMS.

A*:

Remove the power froq, the load and switch to the 200 watt position. Apply power and increase until the voltage across the dummy load is exactly 70.7 volts RMS. Adjust the middle cali- bration pot (red) until the WH-7 indicates exactly 100 watts.

Remove the power from the load and switch to the 2000 watt position. Apply power and increase until the voltage across the dummy load is exactly 224 volts RMS. Adjust the end calihration pot (red) until the WH-7 indicates exactly 1000 watts.

Remove the power from the load. The above procedure cor- rectly calibrates the 20,200, and 2000 watt ranges of the WH-7 and care should be taken not to disturb previous adjustments when calibrating a range.